<!DOCTYPE html>
<html lang="zh-CN">
  <head>
    <meta charset="UTF-8" />
    <title>练习1</title>
    <style type="text/css">
      button {
        border-style: solid;
        border-color:greenyellow;
        float: left;
        background-color: greenyellow;
      }
       button:hover{
        background-color:green;
      }
    </style>
  </head>

  <body>
    <p>四个按钮组:</p>
    <div class="btn-group" style="width: 100%">
      <button style="width: 25%">Apple</button>
      <button style="width: 25%">Samsung</button>
      <button style="width: 25%">Sony</button>
      <button style="width: 25%">HTC</button>
    </div>
  </body>
</html>
